Make some updates to BM bar for MD.

ui/gfx/color_utils.cc

Index: ui/gfx/color_utils.cc
diff --git a/ui/gfx/color_utils.cc b/ui/gfx/color_utils.cc
index b042538c3bf2d672a08f0a4b166fcf6f4efc40d7..9d9a172df703d6053dabb75140f109957b5f18c5 100644
--- a/ui/gfx/color_utils.cc
+++ b/ui/gfx/color_utils.cc
@@ -77,6 +77,10 @@ double ContrastRatio(double foreground_luminance, double background_luminance) {
 
 // ----------------------------------------------------------------------------
 
+double GetContrastRatio(SkColor color_a, SkColor color_b) {
+  return ContrastRatio(RelativeLuminance(color_a), RelativeLuminance(color_b));
+}
+
 unsigned char GetLuminanceForColor(SkColor color) {
   return base::saturated_cast<unsigned char>(
       (0.3 * SkColorGetR(color)) +